My mom occasionally sees people, but her sundowning is more thoughts that have no basis in reality. She started taking Seroquel three and a half years ago. The dosage has gradually increased from 12.5mg a day too 100mg a day. It helps tremendously but it does not work as well for some. It will take trial and error to find something to help her as dementia may also cause problems with how the brain processes medication.
An anti-anxiety medication may help her. Also, tell your friend to make sure his wife is hydrated, has had a snack, and is comfortable as the afternoon goes on.